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Infection and Immunity, May 1999, p. 2491-2496, Vol. 67, No. 5
Channing Laboratory1
and Division of Infectious Disease,
Received 18 November 1998/Returned for modification 3 February
1999/Accepted 18 February 1999
The alpha C protein, a protective surface protein of group B
streptococci (GBS), is present in most non-type III GBS strains. Conjugate vaccines composed of the alpha C protein and type III capsular polysaccharide (CPS) might be protective against most GBS
infections. In this study, the type III CPS was covalently coupled to
full-length, nine-repeat alpha C protein (resulting in III- Group B streptococci (GBS) are the
leading cause of meningitis, pneumonia, and sepsis in neonates
(1). The type-specific capsular polysaccharides (CPS)
expressed on the surface of GBS are considered protective antigens
(23). Thus far, nine CPS serotypes are known: Ia, Ib, II,
III, IV, V, VI, VII, and VIII. Human vaccine trials with CPS of types
Ia, II, and III showed low and variable levels of CPS-specific
antibodies following immunization of volunteers and pregnant women
(2, 3). Coupling of type III CPS to a carrier protein, such
as tetanus toxoid (TT), enhanced the immunogenicity of type III CPS and
resulted in antibody levels that were less variable. Vaccination of
healthy nonpregnant women with a type III CPS-TT (III-TT) conjugate
vaccine elicited a 50-fold increase in type III CPS-specific antibody
levels, while vaccination with an unconjugated type III CPS vaccine
elicited a 7-fold increase (18). Even at lower doses, 90%
of recipients reacted to the III-TT vaccine with a fourfold increase in
type III CPS-specific antibody concentrations, as opposed to only 50%
of recipients of the unconjugated type III CPS vaccine.
Protection by CPS is highly specific, and cross-protection by the
different serotypes does not occur. To be fully effective, a
multivalent vaccine would require the inclusion of several clinically important serotypes. The most prevalent GBS serotypes causing infections in the United States are type Ia (approximately 35 to 50%
of all GBS infections) and type III (approximately 30% of all GBS
infections) (17, 23a). Recently, type V has emerged as the
most common serotype in nonpregnant adults (5).
TT is a component of several other vaccines, and most adults have high
levels of preexisting antibody to it (16). Since TT is not
relevant to GBS infection, it might be advantageous to incorporate a
GBS protein into the vaccine for the purpose of enhancing protection
and expanding the number of strains covered by the vaccine. Replacement
of TT with a protective cell surface protein of GBS might eliminate the
need for many types of CPS in a multivalent GBS vaccine and avoid the
overuse of TT, which may lead to toxicity or suppression of the
anti-CPS antibody response (7, 9, 16).
Among the surface proteins of GBS that confer immunity, the first to be
identified were two molecules designated the alpha and beta C proteins
(4, 21, 35). In addition, the R protein (10, 22),
Rib protein (33), and alpha-like proteins purified from type
III GBS (19) and from type V GBS (20) were
identified. Among these GBS surface proteins, alpha C protein is the
most frequently found in clinical isolates (9a, 17). The
alpha C protein is present in approximately 50% of all clinical
isolates and in approximately 70% of non-type III GBS isolates.
Therefore, the alpha C protein is a potentially valuable replacement
for TT in conjugate vaccines with type III CPS. A type III CPS-alpha C
protein conjugate vaccine could, by itself, be effective in providing
protection against most GBS infections.
The cloned alpha C protein gene (bca) contains nine
identical tandem repeats flanked by N and C termini (29).
However, the size of the protein, which corresponds to the number of
repeats, varies in clinical GBS isolates (25, 28). Using a
neonatal mouse model, we have shown that the number of repeats is
important for vaccine efficacy (11-13). Alpha C proteins
containing 1 or 2 repeats are more protective when used for passive
(11) or active (12) immunization than are alpha C
proteins with 9 or 16 repeats. Alpha C proteins with fewer repeats
seemed to be more immunogenic than alpha C proteins with more repeats
(12). In addition, spontaneous mutants with fewer repeats
could escape from nine-repeat protein-elicited antibodies
(26) but not from one-repeat protein-elicited antibodies
(13).
In this study, two-repeat alpha C protein was conjugated to GBS type
III CPS (resulting in III- Bacterial strains.
Wild-type GBS strain A909
(Ia/C Purification of proteins and polysaccharide.
Recombinant
two- and nine-repeat alpha C proteins were expressed and purified as
described previously (11). TT (Institut Armand Frappier,
Montreal, Quebec, Canada) was purified to its monomeric form as
detailed elsewhere (34). Type III polysaccharide was
purified from GBS strain M781 by a previously described method (34).
Conjugation by reductive amination.
TT was coupled to type
III CPS by reductive amination as detailed in a previous study
(34). In the current study, reductive amination was also
used, with minor modifications, to couple the alpha C proteins (with
two or nine repeats) to type III CPS. In brief, type III CPS was
oxidized with NaIO4. The proportion of sialic acid residues
oxidized was determined by gas chromatography-mass spectrometry of
trimethylsilyl derivatives. Equal amounts of oxidized type III CPS and
alpha C protein were conjugated in 0.2 M
Na2HPO4 (pH 7.2) by use of sodium
cyanoborohydrate, and the mixture was incubated at 37°C for up to 4 days. The conjugation process was monitored by chromatography of the
conjugation sample on a Superose-6 column (Pharmacia, Piscataway, N.J.)
with phosphate-buffered saline, and the A280 was
monitored at the beginning of conjugation and 24, 48, and 66 h
later. Subsequently, the conjugate was separated from free alpha C
protein by gel filtration chromatography (S300 column; Pharmacia) with
phosphate-buffered saline. The void-volume fractions monitored by
A280 were pooled, reduced with sodium
borohydride, dialyzed against water, and lyophilized. The III-TT
conjugate vaccine was produced in a previous study by use of type III
CPS with 25% of the sialic acid residues oxidized (34); the
conjugate vaccine contained 61% (wt/wt) CPS and 39% (wt/wt) protein.
Analysis of the conjugate vaccines.
III- Production of rabbit antisera.
Two New Zealand White female
rabbits (6 to 8 weeks old) were subcutaneously immunized on days 0, 21, and 42 with 50 µg of the III- Immunogenicity of the conjugate vaccines.
Antibodies
elicited to the two- and nine-repeat alpha C proteins by the
unconjugated proteins or by the III- Passive immunization.
The mouse protection study was adapted
from that of Rodewald et al. (31). In our study, groups of
four CD-1 outbred pregnant mice were given 0.5 ml of undiluted rabbit
antiserum by intraperitoneal injection 3 to 4 days before delivery.
Within 48 h of birth, pups were challenged intraperitoneally with
5 × 104 CFU of GBS strain A909 or with 1 × 106 CFU of GBS strain M781 (103 times the 50%
lethal dose, as determined in pilot studies). Survival was assessed
48 h after challenge, and survival data for groups whose dams had
been immunized with different antisera were compared by use of
Fisher's exact test.
Active immunization.
A neonatal mouse model of GBS infection
was used to compare the protective efficacies of the III- III- (ii) Active immunization.
No dose-response effect on antibody
titers to either antigen (type III CPS or nine-repeat alpha C protein)
was observed for mice (Tables 1 and
2). Moreover, the immunogenicity of the
vaccine, as assessed by antibody titers elicited to each of the
components, was moderate to low.
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Alpha C Protein as a Carrier for Type III Capsular
Polysaccharide and as a Protective Protein in Group B
Streptococcal Vaccines
ABSTRACT
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
9r
conjugate vaccine) or to two-repeat alpha C protein (resulting in
III-2r conjugate vaccine) by reductive amination. Initial
experiments with the III-9r vaccine showed that it was poorly
immunogenic in mice with respect to both vaccine antigens and was
suboptimally efficacious in providing protection in mice against
challenge with GBS. Therefore, modified vaccination protocols were used
with the III-2r vaccine. Female mice were immunized three times with
0.5, 5, or 20 µg of the III-2r vaccine with an aluminum hydroxide
adjuvant and bred. Ninety-five percent of neonatal mice born to dams
immunized with the III-2r vaccine survived challenge with GBS
expressing type III CPS, and 60% survived challenge with GBS
expressing wild-type (nine-repeat) alpha C protein; 18 and 17%,
respectively, of mice in the negative control groups survived
(P, <0.0001). These protection levels did not differ
significantly from those obtained with the type III CPS-tetanus toxoid
conjugate vaccine and the unconjugated two-repeat alpha C protein,
which protected 98 and 58% of neonates from infection with GBS
expressing type III CPS or the alpha C protein, respectively. Thus, the
two-repeat alpha C protein in the vaccine was immunogenic and
simultaneously enhanced the immunogenicity of type III CPS. III-
vaccines may be alternatives to GBS polysaccharide-tetanus toxoid
vaccines, eliciting additional antibodies protective against GBS infection.
INTRODUCTION
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
2r vaccine) by reductive amination. We
tested whether this protein could act as a carrier protein for type III
CPS and simultaneously whether it could protect from infection with GBS
expressing nine-repeat alpha C protein. Antisera elicited to the
III-2r vaccine were analyzed for antibodies to type III CPS and
two-repeat alpha C protein by an enzyme-linked immunosorbent assay
(ELISA). Protective efficacy was studied by passive and active
immunization in a neonatal mouse model with GBS strains M781, which
expresses type III CPS but lacks C proteins (III/C
), and
A909, which expresses type Ia CPS and the alpha and loeta C proteins
(Ia/C+
+), for challenge. In a separate
study, type III CPS was coupled to nine-repeat alpha C protein
(resulting in III-9r vaccine) and tested for its immunogenicity and
protective capacity in neonatal mice. Results obtained in each vaccine
study with III-9r or III-2r vaccine were individually compared to
results obtained with the III-TT vaccine, which was included in both studies.
MATERIALS AND METHODS
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
++), which expresses nine repeats,
and GBS strain M781 (III/C) were used in the protection
studies. Escherichia coli HMS174(DE3) and BL21(DE3), which
contain plasmids with different numbers of repeats, were used for the
purification of two- and nine-repeat alpha C proteins. GBS strain M781
was used as a source of type III polysaccharide.
2r and III-9r
vaccines were analyzed for their protein (24) and
carbohydrate (8) contents; purified alpha C protein and type
III CPS were used as the standards. The quality of the conjugate was
tested by sodium dodecyl sulfate (SDS)-polyacrylamide gel
electrophoresis (PAGE) followed by silver staining (30) or
by Western blotting with rabbit antisera to type III CPS and monoclonal
antibody 4G8 to the alpha C protein.
2r vaccine in the presence of
aluminum hydroxide or with 100 µg of the III-9r vaccine in the
presence of complete Freund's adjuvant on day 0; booster doses were
given on days 21 and 42 with incomplete Freund's adjuvant. Serum was
collected before each immunization and again 2 weeks after the last immunization.
2r or III-9r vaccines in
rabbits or mice were measured in an ELISA developed for the alpha C
proteins as described previously (11). Antibodies elicited
to type III CPS by the III-TT, III-2r, and III-9r vaccines in
rabbits or mice were measured by an ELISA developed for this polysaccharide (14).
2r and
III-TT vaccines or to compare those of the III-9r and III-TT
vaccines (31). Groups of four CD-1 outbred mice (6 to 8 weeks old) were immunized intraperitoneally with 0.5, 5, or 20 µg of
the III-2r vaccine or with 2 µg of the III-TT vaccine in the
presence of aluminum hydroxide adjuvant on day 0 and boosted on days 21 and 42. For immunization with the III-9r vaccine, mice were given 5, 10, or 20 µg in the presence of aluminum hydroxide adjuvant and
boosted once (on day 21) instead of twice. Mice were bred 1 week after
the last immunization, and pups (born 4 weeks after the last booster)
were challenged intraperitoneally with 5 × 104 CFU of
GBS strain A909 or with 1 × 106 CFU of GBS strain
M781 (103 times the 50% lethal dose, as determined in a
pilot study) within 48 h of birth. Survival was assessed 48 h
after challenge, and survival data for groups whose dams had been
immunized with different vaccines were compared by use of Fisher's
exact test.
RESULTS
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
9r conjugate vaccine. (i) Analysis of the conjugate
vaccine.
For the III-9r vaccine, 40% of the sialic acid
residues in the polysaccharides were oxidized to create aldehyde groups
for covalent linkage with the 
-amino groups of lysine residues in the alpha C protein. An A280 profile of
Superose-6 fractions as well as an SDS-PAGE analysis of S300 fractions
(Fig. 1) revealed conjugation with a high
degree of cross-linking between the nine-repeat alpha C protein (109 kDa) and type III CPS (150 kDa). The purified III-9r conjugate
vaccine was composed of 51% (wt/wt) CPS and 49% (wt/wt) protein.
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FIG. 1.
Analysis of the conjugate vaccines. (Top) The elution
volumes of uncoupled nine-repeat alpha C protein (Ve 9r)
and of the type III polysaccharide-nine-repeat alpha C protein
conjugate vaccine (Ve III-9r) were 11.4 and 6.8 ml,
respectively. The shift to the left of the protein profile 48 h
after conjugation indicates the formation of high-molecular-weight
polymers. The elution volumes of uncoupled two-repeat alpha C protein
(Ve 2r) and of the type III polysaccharide-two-repeat
alpha C protein conjugate vaccine (Ve III-2r) were 16.6 and 8.2 ml, respectively. The shift to the left of the protein profile
42 h after conjugation indicates the formation of
high-molecular-weight polymers. (Bottom) SDS-PAGE was followed by
silver staining or by Western blotting (with monoclonal antibody 4G8 to
detect the alpha C protein or rabbit antiserum to detect type III CPS);
the results obtained with III-9r conjugation are shown at the lower
left, while those obtained with III-2r conjugation are shown at the
lower right. Molecular masses in kilodaltons are shown to the left of
each panel. For both vaccines, the high-molecular-mass conjugate is
reactive with antibodies to both the protein and the polysaccharide.
TABLE 1.
Immunogenicity and protective efficacy of III- 9r
conjugate vaccine in micea
TABLE 2.
Immunogenicity and protective efficacy of the III- 9r
conjugate vaccine in micea
9r vaccine elicited moderate antibody titers to
type III CPS, neonates were only weakly protected from infection with
GBS strain M781 (29%) (Table 1). Surprisingly, neonates were protected
from infection with GBS strain A909 (62%), despite the low antibody
titers elicited to the nine-repeat alpha C protein component of the
III-9r vaccine (Table 2). The positive controls (III-TT vaccine and
unconjugated nine-repeat alpha C protein) protected 100 and 58% of
neonates from GBS infection, respectively. The negative control
(saline) did not protect neonates from GBS infection.
(iii) Passive immunization.
Antibody titers to type III CPS
and nine-repeat alpha C protein were 51,200 and 6,400, respectively, in
antisera from rabbits immunized with the III-9r vaccine. All
neonates born to dams immunized with these antisera were protected from
infection with GBS strain M781, while 58% were protected from
infection with GBS strain A909 (Table 3).
The positive controls (antisera elicited to III-TT vaccine and
unconjugated nine-repeat alpha C protein) protected 98 and 45% of the
neonates, respectively. The negative control (preimmunization sera) did
not protect neonates from GBS infection. In pups born to control mice
that received saline rather than serum, survival rates were 9% (M781
challenge) and 22% (A909 challenge).
|
III-2r conjugate vaccine. (i) Analysis of the conjugate
vaccine.
We were unable to achieve conjugation of one-repeat alpha
C protein (39 kDa) with type III CPS (data not shown). For the
III-2r vaccine, 40% of the sialic acid residues in the type III CPS
were oxidized, and conjugation with a high degree of cross-linking was
obtained with two-repeat alpha C protein (47 kDa). The III-2r vaccine was composed of 61% (wt/wt) CPS and 39% (wt/wt) protein. An
A280 profile of Superose-6 fractions and an
SDS-PAGE analysis of the purified (S300 column) III-2r conjugate
vaccine are shown in Fig. 1.
(ii) Active immunization.
A clear dose-response effect of the
III-2r vaccine on antibody titers to both antigens (type III CPS and
two-repeat alpha C protein) was observed for mice (Tables
4 and 5).
Although the III-2r vaccine elicited reasonably high antibody titers
to the protein and CPS antigens, the positive controls (purified unconjugated two-repeat alpha C protein and III-TT vaccine) elicited higher antibody titers. Several studies with mice and humans (15, 18) have shown that unconjugated type III CPS is not adequately immunogenic; therefore, the unconjugated antigen was not tested in this
study.
|
|
2r vaccine in neonatal mice was
assessed in the same dose-response experiment as that used to evaluate
its immunogenicity. A dose-response effect on protection levels was
observed. At the highest dose (20 µg/mouse), 95% of neonates were
protected from infection with GBS strain M781 (Table 4), while 60%
were protected from infection with GBS strain A909 (Table 5). The
positive controls (III-TT vaccine and unconjugated two-repeat alpha C
protein) protected 98 and 58% of neonates, respectively. The negative
control (saline with adjuvant) did not significantly protect neonates
from GBS infection.
(iii) Passive immunization.
Antibody titers to type III CPS
and two-repeat alpha C protein were 51,200 and 3,200, respectively, in
antisera from rabbits immunized with the III-2r vaccine. To confirm
the results obtained with active immunization, mice were passively
immunized with rabbit antisera to the III-2r vaccine. Ninety-four
percent of neonates were protected from infection with GBS strain M781,
while 55% were protected from infection with GBS strain A909 (Table
6). The positive controls (antisera
elicited to III-TT vaccine and unconjugated two-repeat alpha C protein)
protected 98 and 55% of neonates, respectively. The negative control
(preimmunization sera) did not significantly protect neonates from GBS
infection. In pups born to control mice that received saline rather
than serum, survival rates were 6% (M781 challenge) and 14% (A909
challenge). In each of the active and passive protection studies,
little variation was observed in survival among litters within the same
treatment groups.
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DISCUSSION |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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Newer vaccines against encapsulated bacteria are based on the
chemical coupling of CPS to carrier proteins. Thus far, only a few
carrier proteins, such as TT or diphtheria toxoid, have been used for
the preparation of these vaccines. Carrier-specific epitope
suppression, in which the antibody response to CPS is reduced by prior
immunization with the carrier protein, has been documented in several
studies (9, 16, 32). Although it has been shown that prior
immunization of mice with TT does not suppress the immune response to
the type III CPS component of the III-TT vaccine (13a),
recent studies with humans (7) suggest that an increase in
the amount of TT
for instance, in multicomponent vaccinesmay reduce
the efficiency of such vaccines. If a protective surface protein from
the same microorganism as the polysaccharide is used as a carrier
protein, the overuse of TT is avoided and protection against more
serotypes may be provided.
Until now, only a few conjugate vaccines containing a protective surface protein and a polysaccharide from the same microorganism have been described. Neisseria meningitidis CPS conjugated to a meningococcal outer membrane vesicle protein from the same organism induced high bactericidal titers in monkeys (36). Another example is a CPS fimbrial protein conjugate vaccine which protected against Porphyromonas gingivalis in mice (6). We previously showed that the surface-associated beta C protein of GBS in a conjugate vaccine with type III CPS successfully protected neonatal mice from GBS expressing beta C protein (27). However, beta C protein is present in only 10% of all clinical isolates of GBS. Since alpha C protein is present in 70% of non-type III GBS strains, a combination of type III CPS and the alpha C protein in one vaccine might be protective against most GBS infections.
In the study presented here, we conjugated GBS type III CPS to a
nine-repeat alpha C protein of GBS by reductive amination and tested
this conjugate vaccine for its immunogenicity and protective efficacy
in mice. It appeared that antibody titers elicited to type III CPS and
nine-repeat alpha C protein by the III-9r vaccine were moderate to
low. In a previous study, we showed that the immunogenicity of the
alpha C protein in mice was inversely related to the number of repeats
(11). In other words, 9- or 16-repeat alpha C protein was
less immunogenic than 1- or 2-repeat alpha C protein. This low
immunogenicity of nine-repeat alpha C protein may have influenced the
immunogenicity of both components in the III-9r vaccine. Of note,
there was no direct correspondence between the dose of III-9r
vaccine and its protective efficacy in active immunization (Tables 1
and 2). With other vaccines, higher doses of carrier proteins have
resulted in diminished protective efficacy (7, 9, 16, 32).
The antibody response to the alpha C protein moiety was so low at all
doses tested that it may have been near a threshold resulting in
variable protection. Because the ELISA does not measure functional
activity, ELISA titers may not correlate directly with protective efficacy.
The III-9r vaccine protected 29% of neonatal mice from GBS
expressing type III CPS and 62% of neonatal mice from GBS expressing nine-repeat alpha C protein. Inhibition with rabbit antiserum raised to
native type III CPS on intact GBS in an ELISA showed no significant
difference between antibody binding to the III-9r vaccine and to
unconjugated type III CPS (data not shown). The implication is that
epitopes in type III CPS, including conformational epitopes, were not
altered by conjugation to the alpha C protein. Moreover, high antibody
titers to type III CPS were elicited in rabbits by the III-9r
vaccine in the presence of Freund's adjuvant, and 100% of pups were
protected from GBS expressing type III CPS by passive immunization with
this rabbit antiserum. This result indicates that the protective
epitope in the type III CPS was still intact after conjugation with the
alpha C protein. Although unconjugated nine-repeat alpha C protein or
the III-TT vaccine protected neonatal mice well from infection with GBS
expressing type III CPS or nine-repeat alpha C protein, respectively,
we could not exclude the possibility that the active immunization schedule used in this study was suboptimal for the III-9r vaccine.
Since 1- or 2-repeat alpha C protein is more immunogenic than 9- or 16-repeat alpha C protein, we initially undertook the conjugation of 1-repeat alpha C protein with type III CPS of GBS. However, this effort was not successful. Successful conjugation between two-repeat alpha C protein (47 kDa, 36 lysine residues) and type III CPS suggests that the molecular mass or the number of lysine residues in the one-repeat alpha C protein (39 kDa, 23 lysine residues) was too low for efficient conjugation. In addition, the conformation of one-repeat alpha C protein, which might differ from that of two-repeat alpha C protein, could reduce the availability of lysine residues.
Since the efficacy of the III-9r vaccine in actively immunized mice
was less than optimal, the immunization schedule used with the
III--2r vaccine included an additional booster dose. Active
immunization of mice with the III-2r vaccine induced high antibody
titers to type III CPS and two-repeat alpha C protein. The observed
protection levels were not significantly different from those obtained
with the III-TT vaccine (98%) and with unconjugated two-repeat alpha C
protein (58%), although the immunizing dose of the III-2r vaccine
was higher. Similar protection levels were obtained by passive
immunization with rabbit antiserum raised to the III-2r vaccine plus
aluminum hydroxide.
In this study, GBS two-repeat alpha C protein was an effective carrier
for the type III CPS and simultaneously added protection against
infection with GBS expressing the alpha C protein. We conclude that the
III-2r vaccine may be useful as an alternative to polysaccharide-TT
conjugate vaccines for GBS and as a model for other conjugate vaccines.
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ACKNOWLEDGMENTS |
|---|
We thank Barbara Reinap for the preparation of the conjugate
vaccines and Liz Gong and Julianne Pinel for technical assistance with
the III-9r conjugate vaccine.
This research was supported by NIH grant AI38424 and NIH contract AI75326.
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FOOTNOTES |
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* Corresponding author. Mailing address: Channing Laboratory, 181 Longwood Ave., Boston, MA 02115. Phone: (617) 525-2677. Fax: (617) 731-1541. E-mail: lmadoff{at}channing.harvard.edu.
Editor: V. A. Fischetti
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REFERENCES |
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Abstract
Introduction
Materials and Methods
Results
Discussion
References
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| 1. | Baker, C. J., and M. S. Edwards. 1995. Group B streptococcal infections, p. 980-1054. In J. S. Remington, and J. O. Klein (ed.), Infectious diseases of the fetus and newborn infant, 4th ed. The W. B. Saunders Co., Philadelphia, Pa. |
| 2. | Baker, C. J., and D. L. Kasper. 1985. Group B streptococcal vaccines. Rev. Infect. Dis. 7:458-467[Medline]. |
| 3. | Baker, C. J., M. A. Rench, M. S. Edwards, R. J. Carpenter, B. M. Hays, and D. L. Kasper. 1988. Immunization of pregnant women with a polysaccharide vaccine of group B Streptococcus. N. Engl. J. Med. 319:1180-1220[Abstract]. |
| 4. | Bevanger, L., and J. A. Maeland. 1979. Complete and incomplete Ibc protein fraction in group B streptococci. Acta Pathol. Microbiol. Scand. Sect. B 87:51-54. |
| 5. | Blumberg, H. M., D. S. Stephens, M. Modansky, M. Erwin, J. Elliot, R. R. Facklam, A. Schuchat, W. Baughman, and M. M. Farley. 1996. Invasive group B streptococcal disease: the emergence of serotype V. J. Infect. Dis. 173:365-373[Medline]. |
| 6. |
Choi, J. I.,
R. E. Schifferle,
F. Yoshimura, and B. W. Kim.
1998.
Capsular polysaccharide-fimbrial protein conjugate vaccine protects against Porphyromonas gingivalis infection in SCID mice reconstituted with human peripheral blood lymphocytes.
Infect. Immun.
66:391-393 |
| 7. |
Dagan, R.,
J. Eskola,
C. Leclerc, and O. Leroy.
1998.
Reduced response to multiple vaccines sharing common protein epitopes that are administered simultaneously to infants.
Infect. Immun.
66:2093-2098 |
| 8. | Dubois, M., K. A. Gilles, J. K. Hamilton, P. A. Rebers, and F. Smith. 1956. Colorimetric method for the determination of sugars and related substances. Anal. Chem. 28:350-356. |
| 9. | Fattom, A., Y. H. Cho, S. Fuller, and R. Naso. 1996. Overload of homologous carrier protein at the site of injection might cause a reduced immunogenicity of capsular polysaccharide conjugate vaccines, p. 160. In Program and abstracts of the 36th Interscience Conference on Antimicrobial Agents and Chemotherapy. American Society for Microbiology, Washington, D.C. |
| 9a. | Ferrieri, P., and A. E. Flores. 1997. Surface protein expression in group B streptococcal invasive isolates. Adv. Exp. Med. Biol. 418:635-637[Medline]. |
| 10. |
Flores, A. E., and P. Ferrieri.
1989.
Molecular species of R-protein antigens produced by clinical isolates of group B streptococci.
J. Clin. Microbiol.
27:1050-1054 |
| 11. | Gravekamp, C., D. S. Horensky, J. L. Michel, and L. C. Madoff. 1996. Variation in repeat number within the alpha C protein of group B streptococci alters antigenicity and protective epitopes. Infect. Immun. 64:3576-3583[Abstract]. |
| 12. | Gravekamp, C., D. L. Kasper, J. L. Michel, D. E. Kling, V. Carey, and L. C. Madoff. 1997. Immunogenicity and protective efficacy of the alpha C protein of group B streptococci are inversely related to the number of repeats. Infect. Immun. 65:5216-5221[Abstract]. |
| 13. |
Gravekamp, C.,
B. Rosner, and L. C. Madoff.
1998.
Deletion of repeats in the alpha C protein enhances the pathogenicity of group B streptococci in immune mice.
Infect. Immun.
66:4347-4354 |
| 13a. | Guttormsen, H. K. Personal communication. |
| 14. | Guttormsen, H. K., C. J. Baker, M. S. Edwards, L. C. Paoletti, and D. L. Kasper. 1996. Quantitative determination of antibodies to type III group B streptococcal polysaccharide. J. Infect. Dis. 173:142-150[Medline]. |
| 15. |
Guttormsen, H. K.,
L. M. Wetzler,
R. W. Finberg, and D. L. Kasper.
1998.
Immunologic memory induced by a glycoconjugate vaccine in a murine adoptive lymphocyte transfer model.
Infect. Immun.
66:2026-2032 |
| 16. | Herzenberg, L. A., and T. Tokuhisa. 1980. Carrier-priming leads to hapten-specific suppression. Nature 285:664-667[Medline]. |
| 17. |
Johnson, D. R., and P. Ferrieri.
1984.
Group B streptococcal Ibc protein antigen: distribution of two determinants in wild-type strains of common serotypes.
J. Clin. Microbiol.
19:506-510 |
| 18. | Kasper, D. L., L. C. Paoletti, M. R. Wessels, H. K. Guttormsen, V. J. Carey, H. J. Jennings, and C. J. Baker. 1996. Immune response to type III group B streptococcal polysaccharide-tetanus toxoid conjugate vaccine. J. Clin. Investig. 98:2308-2314[Medline]. |
| 19. | Kvam, A. I., L. Bevanger, and K. Loseth. 1997. An apparently new strain-variable Streptococcus agalactiae protein. Adv. Exp. Med. Biol. 418:355-357[Medline]. |
| 20. | Lachenauer, C. S., and L. C. Madoff. 1996. A protective surface protein from type V group B streptococci shares N-terminal sequence homology with the alpha C protein. Infect. Immun. 64:4255-4260[Abstract]. |
| 21. | Lancefield, R. C. 1975. Antigens of group B streptococci relation to mouse-protective antibodies and immunity, p. 145-151. In J. B. Robbins, et al. (ed.), New approaches for inducing natural immunity to pyogenic organisms. National Institutes of Health, Bethesda, Md. |
| 22. | Lancefield, R. C., and G. E. Perlmann. 1952. Preparation and properties of a protein (R antigen) occurring in streptococci of group A, type 28 and in certain streptococci of other serological groups. J. Exp. Med. 96:83-97[Abstract]. |
| 23. | Levy, N. J., A. Nicholson-Weller, C. J. Baker, and D. L. Kasper. 1984. Potentiation of virulence by group B streptococcal polysaccharides. J. Infect. Dis. 149:851-860[Medline]. |
| 23a. | Lin, F. Y., J. D. Clemens, P. H. Azimi, J. A. Regan, L. E. Weisman, J. B. Philips III, G. G. Rhoads, P. Clark, R. A. Brenner, and P. Ferrieri. 1998. Capsular polysaccharide types of group B streptococcal isolates from neonates with early-onset systemic infection. J. Infect. Dis. 177:790-792[Medline]. |
| 24. |
Lowry, O. H.,
N. J. Rosebrough,
A. L. Farr, and R. J. Randall.
1951.
Protein measurement with the Folin phenol reagent.
J. Biol. Chem.
193:265-275 |
| 25. |
Madoff, L. C.,
S. Hori,
J. L. Michel,
C. J. Baker, and D. L. Kasper.
1991.
Phenotypic diversity in the alpha C protein of group B streptococcus.
Infect. Immun.
59:2638-2644 |
| 26. |
Madoff, L. C.,
J. L. Michel,
E. W. Gong,
D. E. Kling, and D. L. Kasper.
1996.
Group B streptococci escape host immunity by deletion of tandem repeat elements of the alpha C protein.
Proc. Natl. Acad. Sci. USA
93:4131-4136 |
| 27. | Madoff, L. C., L. C. Paoletti, J. Y. Tai, and D. L. Kasper. 1994. Maternal immunization of mice with group B streptococcal type III polysaccharide-beta C protein conjugate elicits protective antibody to multiple serotypes. J. Clin. Investig. 94:286-292. |
| 28. | Michel, J. L., B. D. Beseth, L. C. Madoff, S. K. Olken, D. L. Kasper, and F. M. Ausubel. 1994. Genotypic diversity and evidence for two distinct classes of the C protein alpha antigen of group B Streptococcus, p. 331-332. In A. Totolian (ed.), Pathogenic streptococci: present and future. Lancer Publications, St. Petersburg, Russia. |
| 29. |
Michel, J. L.,
L. C. Madoff,
K. Olson,
D. E. Kling,
D. L. Kasper, and F. M. Ausubel.
1992.
Large identical tandem repeating units in the C protein alpha antigen gene, bca, of group B streptococci.
Proc. Natl. Acad. Sci. USA
89:10060-10065 |
| 30. | Morrissey, J. H. 1981. Silver stain for proteins in polyacrylamide gels: a modified procedure with enhanced uniform sensitivity. Anal. Biochem. 117:307-310[Medline]. |
| 31. | Rodewald, A. K., A. B. Onderdonk, H. B. Warren, and D. L. Kasper. 1992. Neonatal mouse model of group B streptococcal infection. J. Infect. Dis. 166:635-639[Medline]. |
| 32. | Schutze, M. P., C. Leclerc, M. Jolivet, F. Audibert, and L. Chedid. 1985. Carrier-induced epitopic suppression, a major issue for future synthetic vaccines. J. Immunol. 135:2319-2322[Abstract]. |
| 33. |
Stalhammar-Carlemalm, M.,
L. Stenberg, and G. Lindahl.
1993.
Protein Rib: a novel group B streptococcal cell surface protein that confers protective immunity and is expressed by most strains causing invasive infections.
J. Exp. Med.
177:1593-1603 |
| 34. | Wessels, M. R., L. C. Paoletti, D. L. Kasper, J. L. DiFabio, F. Michon, K. Holme, and H. J. Jennings. 1990. Immunogenicity in animals of a polysaccharide-protein conjugate vaccine against type III group B Streptococcus. J. Clin. Investig. 86:1428-1433. |
| 35. |
Wilkinson, H. W., and R. G. Eagon.
1971.
Type-specific antigens of group B type Ic streptococci.
Infect. Immun.
4:596-604 |
| 36. | Zollinger, W. D., E. E. Moran, S. J. Devi, and C. E. Frasch. 1997. Bactericidal antibody responses of juvenile rhesus monkeys immunized with group B Neisseria meningitidis capsular polysaccharide-protein conjugate vaccines. Infect. Immun. 65:1053-1060[Abstract]. |
Infection and Immunity, May 1999, p. 2491-2496, Vol. 67, No. 5
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